What do we know about the latest email scandal?

That FBI investigators have found a cache of 650,000 email on a laptop belonging to Anthony Weiner, the estranged husband of Huma Abedin, a top Clinton aide. The trove was discovered during a separate criminal sexting investigation into Mr Weiner, a former congressman. They now want to examine these emails to see if they contain classified information. It was not clear from Mr Comey who sent or received the emails or what they were about.

Anthony Weiner and his wife Huma AbedinCredit:
AP

What does that have to do with Mrs Clinton?

It could lead to Mrs Clinton and/or Ms Abedin being indicted for criminally negligent handling of classified material as a result of Mrs Clinton deciding to use a private server for her emails during her time as US Secretary of State.

The FBI announced in July that scores of emails from Mrs Clinton's server contained information that was classified at the time it was sent or received. However, she escaped criminal charges, with Mr Comey saying the FBI had found no evidence of intentional or willful mishandling of classified information, of efforts to obstruct justice or of the deliberate exposure of government secrets. Those were elements that Mr Comey suggested were needed to make a criminal case.

So, new emails determined as classified might do nothing to change the legal risk for anyone involved.

What is the Clinton camp saying?

They are livid. Top aides are accusing the FBI director James Comey – a career Republican - of ripping up the convention that government agencies do not make political interventions within 60 days of an election. Senator Harry Reid went as far as to say Mr Comey might have broken the law by announcing the new steps in the email investigation so close to the election.

"There is no case here," Mrs Clinton insisted on Monday. "Most people have decided a long time ago what they think about all this."

Mr Comey sent an internal email on Friday to FBI employees, saying he was trying to strike a balance between keeping Congress and the public informed and not creating a misleading impression, given that the emails' significance is not yet known.

"In trying to strike that balance, in a brief letter and in the middle of an election season, there is significant risk of being misunderstood," he wrote.

What is the Trump camp saying?

They are triumphant. Mr Trump has seized on the new investigation as proof that they were right to dub Mrs Clinton “crooked Hillary”. Mr Trump, with typical hyperbole, called the news “bigger than Watergate”.

"Her election would mire our government and our country in a constitutional crisis that we cannot afford," Mr Trump declared in Grand Rapids on Monday, saying the former secretary of state might face a criminal trial as president.

Gary Johnson, the Libertarian presidential nominee, said he thought Mrs Clinton could face impeachment over the scandal if she is elected president.

Is the disclosure standard for the FBI?

Not at all. However, the Clinton email investigation was anything but standard.

When Mr Comey announced in July that Mrs Clinton would not face charges, he alluded to the fact the probe was taking place in an election year.

"I am going to include more detail about our process than I ordinarily would, because I think the American people deserve those details in a case of intense public interest," Mr Comey said at an unusual news conference.

The FBI subsequently released investigative files - summaries of witnesses who were interviewed - which are not typically made public.

Mr Comey, a former Republican who is not registered with a political party, has served in government under both Democratic and Republican administrations and speaks repeatedly about the need for the FBI to be accountable to the public.

What happens now?

With 650,000 emails there is no prospect of getting a resolution to the new investigation before polling day. Mr Comey said in his letter to congress the FBI “cannot yet assess” the significance of the material, but there will continuing pressure on him to clarify his momentous intervention.

A US official told The Associated Press the FBI, which had a warrant to begin the review, would be focusing on those deemed pertinent to its earlier Clinton email server investigation. It's unclear how many emails might be relevant.

In its letter to lawmakers, the Justice Department department promised to "continue to work closely with the FBI and together dedicate all necessary resources and take appropriate steps as expeditiously as possible."